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An anonymous reader points out a New York Times article about a traffic analysis program that
"'works by taking note of which cellphone tower a phone is communicating with. It then looks for disruptions in service followed by significant changes in location. If a phone located near Times Square suddenly loses service and reconnects at Prince Street and Broadway 15 minutes later, then it has almost certainly traveled there using the N or R trains.' In another interesting twist, the article briefly notes, 'The system will also include an experiment that uses phones' microphones to sense when riders are on buses.'" The article also mentions a similar project to track buses and trains in Los Angeles.

More importantly, I don't buy the reason why they need to hear anything at all from my phones microphone. I don't see why they need to know what I, or anyone else near me, is saying using this method. Wasn't there are book about something like this???

More worryingly, how did they get access to the noise level from my cell phone's microphone? I don't buy the need for them to know where I am on the bus.

RTFA. It's something they plan to include (as an optional?) in an app that they're developing.It's entirely possible to do all the audio capture and processing on the phone, while only sending a "on the bus" or "not on the bus" packet to Densebrain.

I can't imagine that they'd want to stream audio to their servers and chew through the data plans of their user base.

That's definitely something to worry about. However some phones do have a secondary microphone for the purposes of noise reduction and that one would be the one which would presumably be used. But either way I'm not so sure I'd trust it not to be eavesdropping on me.

The location of all Los Angles buses by GPS is already publicly available [nextbus.com], as well as several other transit systems [homeip.net]. New York is piloting the same system for the B63 5th Avenue bus.

GPS doesn't work underground, but I'm pretty sure the MTA already knows exactly where all its trains are. It's just a matter of making the data public rather then trying to interpolate it using cell phone signals.

Well since I and everybody else paid to ride the bus/subway you would think they would have that data already too.Sounds like a great way to track terrorists or sheep as the case my be.

For the NYC subway, you pay at point of entry, and you walk through a turnstile on exit. There's no data on transfers, or which train you got on. There's also nothing to tie your exit to your entrance. Between knowing where each train is at any given moment and rates at which people are entering and exiting each station you could probably build a decent model of how many people are on any given train. Since in NYC pretty much everybody uses a metrocard now you can probably improve the model a bit by loo

For the NYC subway, you pay at point of entry, and you walk through a turnstile on exit.

Is the fare the same, regardless of the length of the trip? Wikipedia suggests it is.

In the largest European cities I've visited it's not, but I live in London so I'll describe that.

In London there are 9 concentric fare zones (1 to 9, with 1 being the central zone, and few tourists venturing further than Zone 2. Property is often advertised as "5 minutes from a zone 3 station" etc). [PDF map [tfl.gov.uk]]

The fare depends on which zones you travel through, and the time of day (peak/off-peak). e.g.: (from this ridiculou [tfl.gov.uk]

NYC is a single fare for the subway, regardless of how far you're going (much like Paris, or at least, what I remember being told in 7th grade French class oh so many years ago. Our teacher made this sound exotic and unique despite the fact that we lived some 20 miles from the NYC border).

There are also a variety of train systems that bring commuters from various suburbs into NYC, at least some of which operate on some kind of greater distance traveled == greater fare. LIRR for example splits its stations

Which works fine so long as the fare is the same no matter how far you travel. The local link light rail charges differing amounts of money depending upon how far you go, which requires you to swipe when you enter the station and when you leave the destination station. It's a simple enough system then if you want to transfer to a bus you'd have to swipe there again.

Which can be a problem for people with privacy concerns because that information is then available to whomever it is that wants to subpoena it.

You can do that with transit passes. It's not so easy with cash, but with the various cards that are in place they can definitely track those. The local transit service rolled theirs out a while back and they had to deal with the backlash. Apparently, the party paying for the card has access to all the information they have about where the cards are being swiped, which meant that people with company sponsored cards would have to depend upon company policy to guide tracking.

That's why this, to me, deserves the "darkknight" tag - i.e. the "Cell Phone Sonar" system used. There may not be any altitude info, making it not quite a 3D map, but I'm sure the right algorithm would include tower distance > and height, and calculate accordingly.

Or so Alex Morgan Bell hopes. Mr. Bell began designing the system last year, when he was studying electric engineering at Columbia. After trying to get the idea going by himself and luring only several hundred people as users, Mr. Bell joined Densebrain, a Web development company that makes NYCMate, a transit map app (and is perhaps best known for SitorSquat, an app that maps public restrooms).

Seconded -- The town of Corpus Christi, TX had decent WIFI coverage when I lived there. They got me hooked on using it for free before allowing PDQ, and other "providers" to charge me for the service -- I guess the city sponsored WIFI is "rented" to the "providers" that I then must pay to login. Not sure how that's working out for them, but it can't be too bad since the explosion of portable WIFI enabled Android and iOS devices happened shortly afterward (Making it possible to use these devices in WIFI m

Other non-communist cities will not tolerate such a waste of taxpayer dolla... Oh. Rich people will also benefit from this? Then it might be a good idea! Is there any way we can prevent the peasants in the lower 98th percentile from using this system? [/conservolibertarian]

Though these are just aggregates of turnstile data, so they know that X people entered at Times square and Y people exited at prince within about a 4 hour resolution(the scheduled turnstile audits). The only new thing this scheme would add is to tie the specific entrances and exits together. I'm not sure how useful that actually is, you can extrapolate the most frequently ridden lines based on the aggregate entrances and exit

So phones are maybe a reasonable proxy for riders, but it seems to me that the MTA, being a closed system which already has entry controls for fare-collection purposes, just might have more direct ways of getting at ridership, including ones that don't have smartphones. They could instrument their exit gates, too, and correlate them with train arrival times, and figure out which trains are letting off lots of passengers at which stations.

But maybe the phone thing still makes sense if they're not anonymizing

This is an utterly useless app. If transit authorities want to track riders' use of the system they already have a much better sensor network, the cameras that are on board most of their vehicles. Cameras can do a pretty good job of object counting, and if given enough CPU cycles of counting the number and direction of objects moving into and out of a motion detection zone (doorway). That wouldn't even be a hard app to write, and the only additional hardware needed would be for the app to report (wirelessly I'd assume) when the vehicle returns to base.